Saturday, February 18, 2012

Turning on the pole lathe

In our last post we had a pole lathe clamped in a vise. We now have to arrange the return mechanism. But at that point I got an idea. Why not clamp it in a workmate? After all, a workmate is a vise (among other things).
This is the back side of the thing. Not the one the turner sees. OK, now we have to arrange the power train. There is a cord, seen above, which passes around the workpiece. At the lower end it attaches to a treadle, which in my case is an old mop handle. I will have to improve it, but it works as is. At the other end, the cord is tied to a common or garden bungee.
I should have rotated the picture 90 deg ccw!

The ultimate power source is your leg. You push the treadle with your foot. The workpiece rotates. You apply the tool. At the bottom of the stroke, relax your foot. The bungee restores the workpiece. Do not cut during the return stroke, the piece is rotating the wrong way for that. Repeat.

What I am doing in the first picture is called "roughing to cylinder." I am making a rough cylinder out of the piece of branchwood I have set up between centers. This is the hardest part of the whole operation. The piece may look like a cylinder to begin with, but it ain't so. You have to go very gingerly until it is a more or less real cylinder, centered on your, er, centers. Be careful with the screw adjustment. too tight, workpiece hard to spin. Too loose, it flies off. Bummer. A little oil on the points helps a lot. Canola works fine.

Once we have the thing cylindrical, we can start shaping it. I stick with the gouge at this point. I am making a handle for a chisel and I am tapering down the business end of the handle. Thanks to John for the pic, I cannot turn and take pictures at the same time.
The cord rubs on the lathe, not a good idea. I now use a different "lead" (thanks to Gavin on Bodger's for pointing this out) but it did the job at the time. A close-up of the process:
I use two hands for all my turning. One near the toolrest and the other on the handle. The angle at which you hold a gouge (or any other tool is critical. On a gouge you start out with the bevel just rubbing the work. Then you raise the handle ever so slightly. Off comes a beautiful long shaving, if you did it right. If you didn't it may scrape or it may dig in. It takes some practice.

There are other tools you can use. The next most important tool, after a gouge(s) is the skew chisel. Then a ladyfinger gouge. I'll get to those anon.

And I have my revenge on the workmate lathe. You could easily make the bed longer. My bed was limited by the scrap piece of 2x4 I had at hand. All 2x4 scraps are now buried under a meter of snow. You could vary this lathe a lot. But I have achieved my objective, turning a tool handle on a workmate-clamped lathe. Could even clamp it in a bench vise. And finally give credit where credit is due. The original vise-mounted "pole" lathe is due to Jennie Alexander at www.greenwoodworking.com.

The lathe now has a name. It is called Polecat.

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